Real-world safety and effectiveness of inhaled nitric oxide therapy for pulmonary hypertension during the perioperative period of cardiac surgery: a post-marketing study of 2817 patients in Japan

OBJECTIVE

To evaluate the real-world safety and effectiveness of inhaled nitric oxide (INOflo® for Inhalation 800 ppm) for perioperative pulmonary hypertension associated with cardiac surgery in Japan.

METHODS

This was a prospective, non-interventional, all-case, post-marketing study of pediatric and adult patients who received perioperative INOflo with cardiac surgery from November 2015-December 2020. Safety and effectiveness were monitored from INOflo initiation to 48 h after treatment completion or withdrawal. Safety outcomes included adverse drug reactions, blood methemoglobin concentrations, and inspired nitrogen dioxide concentrations over time. Effectiveness outcomes included changes in central venous pressure among pediatrics, mean pulmonary arterial pressure among adults, and the partial pressure of arterial oxygen/fraction of inspired oxygen ratio (PaO2/FiO2) in both populations.

RESULTS

The safety analysis population included 2,817 Japanese patients registered from 253 clinical sites (pediatrics, n = 1375; adults, n = 1442). INOflo was generally well tolerated; 15 and 20 adverse drug reactions were reported in 14 pediatrics (1.0%) and 18 adults (1.2%), respectively. No clinically significant elevations in blood methemoglobin and inspired nitrogen dioxide concentrations were observed. INOflo treatment was associated with significant reductions in both central venous pressure among pediatrics and mean pulmonary arterial pressure among adults, and significant improvements in PaO2/FiO2 among pediatrics and adults with PaO2/FiO2 ≤ 200 at baseline.

CONCLUSIONS

Perioperative INOflo treatment was a safe and effective strategy to improve hemodynamics and oxygenation in patients with pulmonary hypertension during cardiac surgery. These data support the use of INOflo for this indication in Japanese clinical practice.

Effect of nitro-conjugated linoleic acid on the inflammatory response of murine macrophages activated with lipopolysaccharide derived from Prevotella intermedia

Nitro-conjugated linoleic acid (NO2-CLA) has been observed to manifest salutary signaling responses, including anti-inflammatory and antioxidant properties. Here, the authors have explored the influence and underlying mechanisms of NO2-CLA on the proinflammatory reaction of murine macrophages that were challenged with lipopolysaccharide (LPS) derived from Prevotella intermedia, a putative periodontopathic bacterium. Treatment of LPS-activated RAW264.7 cells with NO2-CLA notably dampened the secretion of iNOS-derived NO, IL-1β and IL-6 as well as their gene expressions and significantly enhanced the markers for M2 macrophage polarization. NO2-CLA promoted the HO-1 expression in cells challenged with LPS, and tin protoporphyrin IX, an HO-1 inhibitor, significantly reversed the NO2-CLA-mediated attenuation of NO secretion, but not IL-1β or IL-6. We found that cells treated with NO2-CLA significantly increased mRNA expression of PPAR-γ compared to control cells, and NO2-CLA significantly reverted the decrease in PPAR-γ mRNA caused by LPS. Nonetheless, antagonists to PPAR-γ were unable to reverse the NO2-CLA-mediated suppression of inflammatory mediators. In addition, NO2-CLA did not alter the p38 and JNK activation elicited by LPS. Both NF-κB reporter activity and IκB-α degradation caused by LPS were notably diminished by NO2-CLA. NO2-CLA was observed to interrupt the nuclear translocation and DNA binding of p50 subunits caused by LPS with no obvious alterations in p65 subunits. Further, NO2-CLA attenuated the phosphorylation of STAT1/3 elicited in response to LPS. We propose that NO2-CLA could be considered as a possible strategy for the therapy of periodontal disease, although additional researches are certainly required to confirm this.

Effects of Acute Beetroot Juice and Sodium Nitrate on Selected Blood Metabolites and Response to Transient Ischemia: A Crossover Randomized Clinical Trial

BACKGROUND

Modification of the nitrate (NO3)-nitrite (NO2)-nitric oxide (NO) pathway can be induced by oral intake of inorganic NO3 (NIT) or NO3-rich products, such as beetroot juice (BRJ).

OBJECTIVES

The primary aim of this study was to evaluate the plasma changes in betaine, choline, trimethylamine (TMA), trimethylamine N-oxide (TMAO), and NO3/NO2 (NOx) concentrations over 4 h after single oral ingestion of NIT or BRJ. The flow-mediated skin fluorescence (FMSF) method was applied to measure the changes in nicotinamide adenine dinucleotide reduced form (NADH) in response to transient ischemia and reperfusion. We hypothesized that various sources of NO3 may differently affect endothelial and mitochondrial functions in healthy human subjects.

METHODS

In a randomized crossover trial, 8 healthy young adults ingested 800 mg NO3 from either NIT or BRJ on 2 separate days with ≥3 d apart. Venous blood samples were collected every hour, and FMSF determination was applied bihourly.

RESULTS

Plasma betaine and choline concentrations peaked at 1 h after BRJ ingestion, and remained significantly higher than baseline values at all time points (P < 0.001 and P < 0.001, compared to preingestion values). Over time, BRJ was more effective in increasing NOx compared with NIT (fixed-trial effect P < 0.001). Baseline fluorescence decreased after both NIT and BRJ consumption (fixed-time effect P = 0.005). Transient ischemia and reperfusion response increased because of NO3 consumption (fixed-time effect P = 0.003), with no differences between trials (P = 0.451; P = 0.912; P = 0.819 at 0, 2, and 4 h, respectively).

CONCLUSIONS

Acute ingestion of BRJ elevated plasma betaine and choline, but not TMA and TMAO. Moreover, plasma NOx levels were higher in the BRJ trial than in the NIT trial. Various sources of NO3 positively affected endothelial and mitochondrial functions. This trial was registered at clinicaltrials.gov as NCT05004935.

Nitrous oxide reduction by two partial denitrifying bacteria requires denitrification intermediates that cannot be respired

Denitrification is a form of anaerobic respiration wherein nitrate (NO3-) is sequentially reduced via nitrite (NO2-), nitric oxide, and nitrous oxide (N2O) to dinitrogen gas (N2) by four reductase enzymes. Partial denitrifying bacteria possess only one or some of these four reductases and use them as independent respiratory modules. However, it is unclear if partial denitrifiers sense and respond to denitrification intermediates outside of their reductase repertoire. Here, we tested the denitrifying capabilities of two purple nonsulfur bacteria, Rhodopseudomonas palustris CGA0092 and Rhodobacter capsulatus SB1003. Each had denitrifying capabilities that matched their genome annotation; CGA0092 reduced NO2- to N2, and SB1003 reduced N2O to N2. For each bacterium, N2O reduction could be used both for electron balance during growth on electron-rich organic compounds in light and for energy transformation via respiration in darkness. However, N2O reduction required supplementation with a denitrification intermediate, including those for which there was no associated denitrification enzyme. For CGA0092, NO3- served as a stable, non-catalyzable molecule that was sufficient to activate N2O reduction. Using a β-galactosidase reporter, we found that NO3- acted, at least in part, by stimulating N2O reductase gene expression. In SB1003, NO2- but not NO3- activated N2O reduction, but NO2- was slowly removed, likely by a promiscuous enzyme activity. Our findings reveal that partial denitrifiers can still be subject to regulation by denitrification intermediates that they cannot use.IMPORTANCEDenitrification is a form of microbial respiration wherein nitrate is converted via several nitrogen oxide intermediates into harmless dinitrogen gas. Partial denitrifying bacteria, which individually have some but not all denitrifying enzymes, can achieve complete denitrification as a community by cross-feeding nitrogen oxide intermediates. However, the last intermediate, nitrous oxide (N2O), is a potent greenhouse gas that often escapes, motivating efforts to understand and improve the efficiency of denitrification. Here, we found that at least some partial denitrifying N2O reducers can sense and respond to nitrogen oxide intermediates that they cannot otherwise use. The regulatory effects of nitrogen oxides on partial denitrifiers are thus an important consideration in understanding and applying denitrifying bacterial communities to combat greenhouse gas emissions.

Protective Effect of NO2-OA on Oxidative Stress, Gliosis, and Pro-Angiogenic Response in Müller Glial Cells

Inflammation and oxidative and nitrosative stress are involved in the pathogenesis of proliferative retinopathies (PR). In PR, a loss of balance between pro-angiogenic and anti-angiogenic factors favors the secretion of vascular endothelial growth factor (VEGF). This vascular change results in alterations in the blood-retinal barrier, with extravasation of plasma proteins such as α₂-macroglobulin (α₂M) and gliosis in Müller glial cells (MGCs, such as MIO-M1). It is well known that MGCs play important roles in healthy and sick retinas, including in PR. Nitro-fatty acids are electrophilic lipid mediators with anti-inflammatory and cytoprotective properties. Our aim was to investigate whether nitro-oleic acid (NO₂-OA) is beneficial against oxidative stress, gliosis, and the pro-angiogenic response in MGCs. Pure synthetic NO₂-OA increased HO-1 expression in a time- and concentration-dependent manner, which was abrogated by the Nrf2 inhibitor trigonelline. In response to phorbol 12-myristate 13-acetate (PMA) and lipopolysaccharide (LPS), NO₂-OA prevented the ROS increase and reduced the gliosis induced by α₂M. Finally, when hypoxic MGCs were incubated with NO₂-OA, the increase in VEGF mRNA expression was not affected, but under hypoxia and inflammation (IL-1β), NO₂-OA significantly reduced VEGF mRNA levels. Furthermore, NO₂-OA inhibited endothelial cell (BAEC) tubulogenesis. Our results highlight NO₂-OA's protective effect on oxidative damage, gliosis; and the exacerbated pro-angiogenic response in MGCs.

Effects of Combined Inorganic Nitrate and Nitrite Supplementation on Cardiorespiratory Fitness and Skeletal Muscle Oxidative Capacity in Type 2 Diabetes: A Pilot Randomized Controlled Trial

Nitric oxide (NO) stimulates mitochondrial biogenesis in skeletal muscle. However, NO metabolism is disrupted in individuals with type 2 diabetes mellitus (T2DM) potentially contributing to their decreased cardiorespiratory fitness (i.e., VO2max) and skeletal muscle oxidative capacity. We used a randomized, double-blind, placebo-controlled, 8-week trial with beetroot juice containing nitrate (NO3−) and nitrite (NO2−) (250 mg and 20 mg/day) to test potential benefits on VO2max and skeletal muscle oxidative capacity in T2DM. T2DM (N = 36, Age = 59 ± 9 years; BMI = 31.9 ± 5.0 kg/m2) and age- and BMI-matched non-diabetic controls (N = 15, Age = 60 ± 9 years; BMI = 29.5 ± 4.6 kg/m2) were studied. Mitochondrial respiratory capacity was assessed in muscle biopsies from a subgroup of T2DM and controls (N = 19 and N = 10, respectively). At baseline, T2DM had higher plasma NO3− (100%; p < 0.001) and lower plasma NO2− levels (−46.8%; p < 0.0001) than controls. VO2max was lower in T2DM (−26.4%; p < 0.001), as was maximal carbohydrate- and fatty acid-supported oxygen consumption in permeabilized muscle fibers (−26.1% and −25.5%, respectively; p < 0.05). NO3−/NO2− supplementation increased VO2max (5.3%; p < 0.01). Further, circulating NO2−, but not NO3−, positively correlated with VO2max after supplementation (R2= 0.40; p < 0.05). Within the NO3−/NO2− group, 42% of subjects presented improvements in both carbohydrate- and fatty acid-supported oxygen consumption in skeletal muscle (vs. 0% in placebo; p < 0.05). VO2max improvements in these individuals tended to be larger than in the rest of the NO3−/NO2− group (1.21 ± 0.51 mL/(kg*min) vs. 0.31 ± 0.10 mL/(kg*min); p = 0.09). NO3−/NO2− supplementation increases VO2max in T2DM individuals and improvements in skeletal muscle oxidative capacity appear to occur in those with more pronounced increases in VO2max.

High-Dose Nitrate Supplementation Attenuates the Increased Blood Pressure Responses to Isometric Blood Flow Restriction Exercise in Healthy Males

The effect of nitrate (NO3−) supplementation on blood pressure (BP) responses during large muscle mass isometric and ischaemic exercise in healthy young adults is unclear. The aim of the present study was to assess the effect of 5-day supplementation of NO3− on BP responses during a short isometric contraction and a sustained ischaemic contraction. In a randomised, double-blinded, crossover design, 14 healthy active young adults underwent BP measurements after 5 days of either NO3− (NIT) or placebo (PLA) supplementation. Beat-by-beat BP was measured at pre- and post-exercise rest, and during a short (20 s) isometric contraction at 25% maximal strength and throughout a sustained ischaemic contraction. Plasma nitrite (NO2−) concentration increased significantly after NO3− supplementation compared to placebo (475 ± 93 nmol·L−1 vs. 198 ± 46 nmol·L−1, p < 0.001, d = 3.37). Systolic BP was significantly lower at pre- (p = 0.051) and post-exercise rest (p = 0.006), during a short isometric contraction (p = 0.030), and throughout a sustained ischaemic contraction (p = 0.040) after NO3− supplementation. Mean arterial pressure was significantly lower at pre- (p = 0.004) and post-exercise rest (p = 0.043), during a short isometric contraction (p = 0.041), and throughout a sustained ischaemic contraction (p = 0.021) after NO3− supplementation. Diastolic BP was lower at pre-exercise rest (p = 0.032), but not at post-exercise rest, during a short isometric contraction, and during a sustained ischaemic contraction (all p > 0.05). Five days of NO3− supplementation elevated plasma NO2− concentration and reduced BP during a short isometric contraction and a sustained ischaemic contraction in healthy adults. These observations indicate that multiple-day nitrate supplementation can decrease BP at rest and attenuate the increased BP response during isometric exercise. These findings support that NO3− supplementation is an effective nutritional intervention in reducing SBP and MAP in healthy young males during submaximal exercise.

GW9662, a peroxisome proliferator-activated receptor gamma antagonist, attenuates the development of non-alcoholic fatty liver disease

BACKGROUND AND AIMS

Insulin resistance is among the key risk factors for the development of non-alcoholic fatty liver disease (NAFLD). Recently, it has been reported that GW9662, shown to be a potent peroxisome proliferator-activated receptor gamma (PPARγ) antagonist, may improve insulin sensitivity in settings of type 2 diabetes. Here, we determined the effects of GW9662 on the development of NAFLD and molecular mechanisms involved.

METHODS

Female C57BL/6J mice were pair-fed either a liquid control diet (C) or a fat-, fructose- and cholesterol-rich diet (FFC) for 8 weeks while either being treated with GW9662 (1 mg/kg body weight; C+GW9662 and FFC+GW9662) or vehicle (C and FFC) i.p. three times weekly. Indices of liver damage and inflammation, parameters of glucose metabolism and portal endotoxin levels were determined. Lipopolysaccharide (LPS)-challenged J774A.1 cells were treated with 10 μM GW9662.

RESULTS

Despite similar caloric intake the development of NAFLD and insulin resistance were significantly attenuated in FFC+GW9662-treated mice when compared to FFC-fed animals. Bacterial endotoxin levels in portal plasma were almost similarly increased in both FFC-fed groups while expressions of toll-like receptor 4 (Tlr4), myeloid differentiation primary response 88 (Myd88) and interleukin 1 beta (Il1b) as well as nitrite (NO₂^-) concentration in liver were significantly higher in FFC-fed mice than in FFC+GW9662-treated animals. In J774A.1 cells, treatment with GW9662 significantly attenuated LPS-induced expression of Il1b, interleukin 6 (Il6) and inducible nitric oxide synthase (iNos) as well as NO₂^- formation.

CONCLUSION

In summary, our data suggest that the PPARγ antagonist GW9662 attenuates the development of a diet-induced NAFLD and that this is associated with a protection against the activation of the TLR4 signaling cascade.

Effect of methomyl on water quality, growth performance and antioxidant system in liver of GIFT (Oreochromis niloticus) in the presence of peppermint (Mentha haplocalyx Briq.) as a floating bed

This study was conducted to investigate the effect of methomyl (MET) on water quality, growth and antioxidant system of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) in the presence of peppermint as a floating bed. The concentration of NH3-N, NO2--N, NO3--N and TP in T3 (with 200 g wet peppermint) was significantly lower (P < 0.05) than that in T2 (100 g), T1 (50 g) and control, and the nutrient removal rates were 61.90%, 31.59%, 59.86% and 45.92% in 20 days, respectively. Juveniles GIFT (5.1 ± 0.2 g) were exposed to sub-lethal concentrations of 0.2, 2.0, 20 and 200 µg/L of MET for 45 days. After 6 weeks of a feeding trial, percentage weight gain (PWG), specific growth rate (SGR) and feed conversion ratio (FCR) were significantly decreased in 0.2, 2.0, 20 µg/L MET groups respectively and increased in the 200 µg/L MET group. Compared with the control, no significant changes in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) were detected in the 0.2 µg/L group. The significant increase in activities of SOD, CAT and GPx was accompanied by a diminution in reduced glutathione (GSH) levels resulting with tilapia exposed to 2.0, 20, or 200 µg/L for 45 days. The highest rates observed in SOD, CAT, GPx were 157.63%, 164.05% and 167.46% of the control respectively, and the lowest inhibition rate in GSH was 66.42% of the control. Peppermint as a floating bed can alleviate the adverse effects of MET, such as growth retardation and oxidative stress.

Comprehensive Transcriptome Analysis of Rare Carpinus putoensis Plants under NO2 stress

We evaluated a transcriptome using high-throughput Illumina HiSeq sequencing and related it to the morphology, leaf anatomy, and physiological parameters of Carpinus putoensis putoensis under NO₂ stress. The molecular mechanism of the C. putoensis NO₂ stress response was evaluated using sequencing data. NO₂ stress adversely affected the morphology, leaf anatomy, and total peroxidase (POD) activity. Through RNA-seq analysis, we used NCBI to compare the transcripts with nine databases and obtained their functional annotations. We annotated up to 2255 million clean Illumina paired-end RNA-seq reads, and 250,200 unigene sequences were assembled based on the resulting transcriptome data. More than 89% of the C. putoensis transcripts were functionally annotated. Under NO₂ stress, 1119 genes were upregulated and 1240 were downregulated. According to the KEGG pathway and GO analyses, photosynthesis, chloroplasts, plastids, and the stimulus response are related to NO₂ stress. Additionally, NO₂ stress changed the expression of POD families, and the HPL2, HPL1, and POD genes exhibited high expression. The transcriptome analysis of C. putoensis leaves under NO₂ stress supplies a reference for studying the molecular mechanism of C. putoensis resistance to NO₂ stress. The given transcriptome data represent a valuable resource for studies on plant genes, which will contribute towards genome annotations during future genome projects.

Nitrogen-Doped Titanium Dioxide Mixed with Calcium Peroxide and Methylcellulose for Dental Bleaching under Visible Light Activation

The available tooth whitening products in the market contain high concentrations of hydrogen peroxide (H₂O₂) as an active ingredient. Therefore, in order to curb the high H₂O₂ concentration and instability of liquid H₂O₂, this study evaluated the efficacy and cytotoxicity of the bleaching gel composed of 10% calcium peroxide (CaO₂) and visible-light-activating nitrogen-doped titanium dioxide (N-TiO₂) with methyl cellulose as a thickener. Extracted bovine teeth were discolored using coffee and black tea stain solution and were divided into two groups (n = 6). Bleaching was performed thrice on each tooth specimen in both the groups, with one minute of visible light irradiation during each bleaching time. The CIELAB L*a*b* values were measured pre- and post-bleaching. The N-TiO₂ calcinated at 350 °C demonstrated a shift towards the visible light region by narrowing the band gap energy from 3.23 eV to 2.85 eV. The brightness (ΔL) and color difference (ΔE) increased as bleaching progressed each time in both the groups. ANOVA results showed that the number of bleaching significantly affected ΔE (p < 0.05). The formulated bleaching gel exhibits good biocompatibility and non-toxicity upon exposure to 3T3 cells. Our findings showed that CaO₂-based bleaching gel at neutral pH could be a stable, safe, and effective substitute for tooth whitening products currently available in the market.

Multicenter Ozone Study in oldEr Subjects (MOSES): Part 2. Effects of Personal and Ambient Concentrations of Ozone and Other Pollutants on Cardiovascular and Pulmonary Function

INTRODUCTION

The Multicenter Ozone Study of oldEr Subjects (MOSES) was a multi-center study evaluating whether short-term controlled exposure of older, healthy individuals to low levels of ozone (O3) induced acute changes in cardiovascular biomarkers. In MOSES Part 1 (MOSES 1), controlled O3 exposure caused concentration-related reductions in lung function with evidence of airway inflammation and injury, but without convincing evidence of effects on cardiovascular function. However, subjects' prior exposures to indoor and outdoor air pollution in the few hours and days before each MOSES controlled O3 exposure may have independently affected the study biomarkers and/or modified biomarker responses to the MOSES controlled O3 exposures.

METHODS

MOSES 1 was conducted at three clinical centers (University of California San Francisco, University of North Carolina, and University of Rochester Medical Center) and included healthy volunteers 55 to 70 years of age. Consented participants who successfully completed the screening and training sessions were enrolled in the study. All three clinical centers adhered to common standard operating procedures and used common tracking and data forms. Each subject was scheduled to participate in a total of 11 visits: screening visit, training visit, and three sets of exposure visits consisting of the pre-exposure day, the exposure day, and the post-exposure day. After completing the pre-exposure day, subjects spent the night in a nearby hotel. On exposure days, the subjects were exposed for 3 hours in random order to 0 ppb O3 (clean air), 70 ppb O3, and 120 ppm O3. During the exposure period the subjects alternated between 15 minutes of moderate exercise and 15 minutes of rest. A suite of cardiovascular and pulmonary endpoints was measured on the day before, the day of, and up to 22 hours after each exposure.

In MOSES Part 2 (MOSES 2), we used a longitudinal panel study design, cardiopulmonary biomarker data from MOSES 1, passive cumulative personal exposure samples (PES) of O3 and nitrogen dioxide (NO2) in the 72 hours before the pre-exposure visit, and hourly ambient air pollution and weather measurements in the 96 hours before the pre-exposure visit. We used mixed-effects linear regression and evaluated whether PES O3 and NO2 and these ambient pollutant concentrations in the 96 hours before the pre-exposure visit confounded the MOSES 1 controlled O3 exposure effects on the pre- to post-exposure biomarker changes (Aim 1), whether they modified these pre- to post-exposure biomarker responses to the controlled O3 exposures (Aim 2), whether they were associated with changes in biomarkers measured at the pre-exposure visit or morning of the exposure session (Aim 3), and whether they were associated with differences in the pre- to post-exposure biomarker changes independently of the controlled O3 exposures (Aim 4).

RESULTS

Ambient pollutant concentrations at each site were low and were regularly below the National Ambient Air Quality Standard levels. In Aim 1, the controlled O3 exposure effects on the pre- to post-exposure biomarker differences were little changed when PES or ambient pollutant concentrations in the previous 96 hours were included in the model, suggesting these were not confounders of the controlled O3 exposure/biomarker difference associations. In Aim 2, effects of MOSES controlled O3 exposures on forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were modified by ambient NO2 and carbon monoxide (CO), and PES NO2, with reductions in FEV1 and FVC observed only when these concentrations were "Medium" or "High" in the 72 hours before the pre-exposure visit. There was no such effect modification of the effect of controlled O3 exposure on any other cardiopulmonary biomarker.

As hypothesized for Aim 3, increased ambient O3 concentrations were associated with decreased pre-exposure heart rate variability (HRV). For example, high frequency (HF) HRV decreased in association with increased ambient O3 concentrations in the 96 hours before the pre-exposure visit (-0.460 ln[ms2]; 95% CI, -0.743 to -0.177 for each 10.35-ppb increase in O3; P = 0.002). However, in Aim 4 these increases in ambient O3 were also associated with increases in HF and low frequency (LF) HRV from pre- to post-exposure, likely reflecting a "recovery" of HRV during the MOSES O3 exposure sessions. Similar patterns across Aims 3 and 4 were observed for LF (the other primary HRV marker), and standard deviation of normal-to-normal sinus beat intervals (SDNN) and root mean square of successive differences in normal-to-normal sinus beat intervals (RMSSD) (secondary HRV markers).

Similar Aim 3 and Aim 4 patterns were observed for FEV1 and FVC in association with increases in ambient PM with an aerodynamic diameter ≤ 2.5 μm (PM2.5), CO, and NO2 in the 96 hours before the pre-exposure visit. For Aim 3, small decreases in pre-exposure FEV1 were significantly associated with interquartile range (IQR) increases in PM2.5 concentrations in the 1 hour before the pre-exposure visit (-0.022 L; 95% CI, -0.037 to -0.006; P = 0.007), CO in the 3 hours before the pre-exposure visit (-0.046 L; 95% CI, -0.076 to -0.016; P = 0.003), and NO2 in the 72 hours before the pre-exposure visit (-0.030 L; 95% CI, -0.052 to -0.008; P = 0.007). However, FEV1 was not associated with ambient O3 or sulfur dioxide (SO2), or PES O3 or NO2 (Aim 3). For Aim 4, increased FEV1 across the exposure session (post-exposure minus pre-exposure) was marginally significantly associated with each 4.1-ppb increase in PES O3 concentration (0.010 L; 95% CI, 0.004 to 0.026; P = 0.010), as well as ambient PM2.5 and CO at all lag times. FVC showed similar associations, with patterns of decreased pre-exposure FVC associated with increased PM2.5, CO, and NO2 at most lag times, and increased FVC across the exposure session also associated with increased concentrations of the same pollutants, reflecting a similar recovery. However, increased pollutant concentrations were not associated with adverse changes in pre-exposure levels or pre- to post-exposure changes in biomarkers of cardiac repolarization, ST segment, vascular function, nitrotyrosine as a measure of oxidative stress, prothrombotic state, systemic inflammation, lung injury, or sputum polymorphonuclear leukocyte (PMN) percentage as a measure of airway inflammation.

CONCLUSIONS

Our previous MOSES 1 findings of controlled O3 exposure effects on pulmonary function, but not on any cardiovascular biomarker, were not confounded by ambient or personal O3 or other pollutant exposures in the 96 and 72 hours before the pre-exposure visit. Further, these MOSES 1 O3 effects were generally not modified, blunted, or lessened by these same ambient and personal pollutant exposures. However, the reductions in markers of pulmonary function by the MOSES 1 controlled O3 exposure were modified by ambient NO2 and CO, and PES NO2, with reductions observed only when these pollutant concentrations were elevated in the few hours and days before the pre-exposure visit. Increased ambient O3 concentrations were associated with reduced HRV, with "recovery" during exposure visits. Increased ambient PM2.5, NO2, and CO were associated with reduced pulmonary function, independent of the MOSES-controlled O3 exposures. Increased pollutant concentrations were not associated with pre-exposure or pre- to post-exposure changes in other cardiopulmonary biomarkers. Future controlled exposure studies should consider the effect of ambient pollutants on pre-exposure biomarker levels and whether ambient pollutants modify any health response to a controlled pollutant exposure.

Strategy to achieve a 5-log Salmonella inactivation in tender coconut water using high voltage atmospheric cold plasma (HVACP)

This study examined high voltage atmospheric cold plasma (HVACP) technology as a non-thermal intervention for inactivating Salmonella enterica serovar Typhimurium LT2 (ST2) in tender coconut water (TCW). Treatment with HVACP in air at 90 kV for 120 s inactivated 1.30 log₁₀ of ST2. Development of a TCW stimulant suggested an interfering role of magnesium and phosphate salts with HVACP inactivation. Generation of reactive gas species, viz. ozone and hydrogen peroxides were found to be responsible for microbial inactivation. The addition of 400 ppm citric acid to the TCW effectively reduced ST2 by 5 log₁₀ during HVACP treatment. Under these conditions, higher cellular leakage and morphological damage were observed in ST2. Minimal physico-chemical changes in TCW were observed with HVACP treatment, except for an 84.35% ascorbic acid loss (added externally). These results demonstrate a potential pathway for developing highly effective cold plasma treatments to preserve fruit and vegetable juices.

Nitrate, but not nitrite, derived from nitrogen dioxide accumulates in Arabidopsis leaves following exposure to 15N-labeled nitrogen dioxide

It is known that when plant leaves are exposed to exogenously applied nitrogen dioxide (NO2), nitrogen derived from NO2 is reduced to amino acid nitrogen. However, whether this is the sole metabolic fate of exogenously applied NO2 is unclear. In this study, Arabidopsis leaves were exposed to 4 ppm 15N-labeled NO2 for 4 h in light, followed by capillary ion analysis and elemental analysis-mass spectrometry with an elemental analyzer connected directly to a mass spectrometer. We found that leaf cells exposed to 15N-labeled NO2 accumulated a large amount of 15N-labeled nitrate. Neither 15N-labeled nitrite nor endogenous nitrite was present in exposed leaves. It is likely that exogenously applied NO2 is first converted to nitrite, and that nitrite is oxidized to nitrate in Arabidopsis leaf cells. The complete disappearance of nitrite derived from exogenously applied NO2 and endogenous nitrite supports this mechanism.

Short-Term Exposure to Nitrogen Dioxide Provides Basal Pathogen Resistance

Nitrogen dioxide (NO2) forms in plants under stress conditions, but little is known about its physiological functions. Here, we explored the physiological functions of NO2 in plant cells using short-term fumigation of Arabidopsis (Arabidopsis thaliana) for 1 h with 10 µL L-1 NO2. Although leaf symptoms were absent, the expression of genes related to pathogen resistance was induced. Fumigated plants developed basal disease resistance, or pattern-triggered immunity, against the necrotrophic fungus Botrytis cinerea and the hemibiotrophic bacterium Pseudomonas syringae Functional salicylic acid and jasmonic acid (JA) signaling pathways were both required for the full expression of NO2-induced resistance against B. cinerea An early peak of salicylic acid accumulation immediately after NO2 exposure was followed by a transient accumulation of oxophytodienoic acid. The simultaneous NO2-induced expression of genes involved in jasmonate biosynthesis and jasmonate catabolism resulted in the complete suppression of JA and JA-isoleucine (JA-Ile) accumulation, which was accompanied by a rise in the levels of their catabolic intermediates 12-OH-JA, 12-OH-JA-Ile, and 12-COOH-JA-Ile. NO2-treated plants emitted the volatile monoterpene α-pinene and the sesquiterpene longifolene (syn. junipene), which could function in signaling or direct defense against pathogens. NO2-triggered B. cinerea resistance was dependent on enhanced early callose deposition and CYTOCHROME P450 79B2 (CYP79B2), CYP79B3, and PHYTOALEXIN DEFICIENT3 gene functions but independent of camalexin, CYP81F2, and 4-OH-indol-3-ylmethylglucosinolate derivatives. In sum, exogenous NO2 triggers basal pathogen resistance, pointing to a possible role for endogenous NO2 in defense signaling. Additionally, this study revealed the involvement of jasmonate catabolism and volatiles in pathogen immunity.

Maternal exposure to NO2 enhances airway sensitivity to allergens in BALB/c mice through the JAK-STAT6 pathway

Previous studies have indicated that nitrogen dioxide (NO₂) exposure could increase airway sensitivity to allergens for children. Recently, fetal stress was proposed as a crucial factor for allergic airway response occurring in offspring. Considering that there is inadequate evidence linking maternal NO₂ exposure to offspring airway sensitivity to allergens, pregnant Balb/c mice were exposed daily to 2.5 ppm NO₂ throughout the gestation period; then, the offspring were challenged to an allergen (ovalbumin, OVA) to evaluate airway sensitivity. For air + saline group and air + OVA group, offspring mice were maternally exposed to clean air followed by treatment with saline and OVA, respectively, in adulthood. For NO₂ + saline group and NO₂ + OVA group, offspring mice were maternally exposed to NO₂ followed by treatment with saline and OVA, respectively, in adulthood. The results showed that maternal NO₂ exposure increased the level of OVA-immunoglobulin (Ig) E in serum and caused airway hyper-responsiveness and pathological changes in offspring. Furthermore, maternal NO₂ exposure altered the expression of pro-inflammatory factors and impaired the T helper (Th) 1/Th2 balance. In addition, janus kinase)-signal transducer and activator of transcription 6 pathway participated in OVA-induced airway sensitivity of offspring. Our study showed that the potential risk of airway sensitivity to allergens in offspring is enhanced by maternal NO₂ exposure and proposed a possible mechanism for preventing, alleviating, and evaluating the outcomes in polluted environments.

Nitrogen dioxide radicals mediated mineralization of perfluorooctanoic acid in aqueous nitrate solution with UV irradiation

Effective decomposition of perfluorooctanoic acid (PFOA) has received increasing attention in recent years because of its global occurrence and resistance to most conventional treatment processes. In this study, the complete mineralization of PFOA was achieved by the UV-photolysis of nitrate aqueous solution (UV/Nitrate), where the in-situ generated nitrogen dioxide radicals (NO₂) efficiently mediated the degradation of PFOA. In particular, when the twinborn hydroxyl radicals were scavenged, the production of more NO₂ radicals realized the complete mineralization of PFOA. DFT calculations further confirm the feasibility of PFOA removal with NO₂. Near-stoichiometric equivalents of fluoride released rather than the related intermediates were detected in solution after decomposition of PEOA, further demonstrating the complete degradation of PFOA. Possible PFOA degradation pathways were proposed on the basis of experimental results. This work offers an efficient strategy for the complete mineralization of perfluorinated chemicals, and also sheds light on the indispensable roles of nitrogen dioxide radicals for environmental pollutants removal.

The Dose-Response Association between Nitrogen Dioxide Exposure and Serum Interleukin-6 Concentrations

Systemic inflammation is an integral part of chronic obstructive pulmonary disease (COPD), and air pollution is associated with cardiorespiratory mortality, yet the interrelationships are not fully defined. We examined associations between nitrogen dioxide (NO₂) exposure (as a marker of traffic-related air pollution) and pro-inflammatory cytokines, and investigated effect modification and mediation by post-bronchodilator airflow obstruction (post-BD-AO) and cardiovascular risk. Data from middle-aged participants in the Tasmanian Longitudinal Health Study (TAHS, n = 1389) were analyzed by multivariable logistic regression, using serum interleukin (IL)-6, IL-8 and tumor necrosis factor-α (TNF-α) as the outcome. Mean annual NO₂ exposure was estimated at residential addresses using a validated satellite-based land-use regression model. Post-BD-AO was defined by post-BD forced expiratory ratio (FEV₁/FVC) < lower limit of normal, and cardiovascular risk by a history of either cerebrovascular or ischaemic heart disease. We found a positive association with increasing serum IL-6 concentration (geometric mean 1.20 (95% CI: 1.1 to 1.3, p = 0.001) per quartile increase in NO₂). This was predominantly a direct relationship, with little evidence for either effect modification or mediation via post-BD-AO, or for the small subgroup who reported cardiovascular events. However, there was some evidence consistent with serum IL-6 being on the causal pathway between NO₂ and cardiovascular risk. These findings raise the possibility that the interplay between air pollution and systemic inflammation may differ between post-BD airflow obstruction and cardiovascular diseases.

Pollen of common ragweed (Ambrosia artemisiifolia L.): Illumina-based de novo sequencing and differential transcript expression upon elevated NO2/O3

Common ragweed (Ambrosia artemisiifolia L.) is a highly allergenic annual ruderal plant and native to Northern America, but now also spreading across Europe. Air pollution and climate change will not only affect plant growth, pollen production and duration of the whole pollen season, but also the amount of allergenic encoding transcripts and proteins of the pollen. The objective of this study was to get a better understanding of transcriptional changes in ragweed pollen upon NO₂ and O₃ fumigation. This will also contribute to a systems biology approach to understand the reaction of the allergenic pollen to air pollution and climate change. Ragweed plants were grown in climate chambers under controlled conditions and fumigated with enhanced levels of NO₂ and O₃. Illumina sequencing and de novo assembly revealed significant differentially expressed transcripts, belonging to different gene ontology (GO) terms that were grouped into biological process and molecular function. Transcript levels of the known Amb a ragweed encoding allergens were clearly up-regulated under elevated NO₂, whereas the amount of allergen encoding transcripts was more variable under elevated O₃ conditions. Moreover transcripts encoding allergen known from other plants could be identified. The transcriptional changes in ragweed pollen upon elevated NO₂ fumigation indicates that air pollution will alter the transcriptome of the pollen. The changed levels of allergenic encoding transcripts may have an influence on the total allergenic potential of ragweed pollen.

Nitrite is the driver, phytohormones are modulators while NO and H2O2 act as promoters of NO2-induced cell death

This study aimed to understand the molecular mechanisms of nitrogen dioxide (NO₂)-induced toxicity and cell death in plants. Exposure of Arabidopsis to high concentrations of NO₂ induced cell death in a dose-dependent manner. No leaf symptoms were visible after fumigation for 1 h with 10 parts per million (ppm) NO₂ However, 20 ppm NO₂ caused necrotic lesion formation and 30 ppm NO₂ complete leaf collapse, which had already started during the 1 h fumigation period. NO₂ fumigation resulted in a massive accumulation of nitrite and in protein modifications by S-nitrosylation and tyrosine nitration. Nitric oxide (NO) at 30 ppm did not trigger leaf damage or any of the effects observed after NO₂ fumigation. The onset of NO₂-induced cell death correlated with NO and hydrogen peroxide (H₂O₂) signaling and a decrease in antioxidants. NO- and H₂O₂-accumulating mutants were more sensitive to NO₂ than wild-type plants. Accordingly, experiments with specific scavengers confirmed that NO and H₂O₂ are essential promoters of NO₂-induced cell death. Leaf injection of 100 mM nitrite caused an increase in S-nitrosylation, NO, H₂O₂, and cell death suggesting that nitrite functioned as a mediator of NO₂-induced effects. A targeted screening of phytohormone mutants revealed a protective role of salicylic acid (SA) signaling in response to NO₂ It was also shown that phytohormones were modulators rather than inducers of NO₂-induced cell death. The established experimental set-up is a suitable system to investigate NO₂ and cell death signaling in large-scale mutant screens.

Light-triggered selective nitration of PsbO1 in isolated Arabidopsis thylakoid membranes is inhibited by photosynthetic electron transport inhibitors

PsbO1 is exclusively nitrated when isolated thylakoid membranes are incubated in a buffer bubbled with nitrogen dioxide (NO₂) containing NO₂ and nitrite. NO₂ is the primary intermediate for this selective nitration. Isolated thylakoid membranes were incubated in NO₂-bubbled buffer at 25°C in the light or dark. Protein analysis confirmed the selective nitration of PsbO1. Illumination was found to be essential in PsbO1 nitration. A nitration mechanism whereby nitratable tyrosine residues of PsbO1 are, prior to nitration, selectively photo-oxidized by photosynthetic electron transport to tyrosyl radicals to combine with NO₂ to form 3-nitrotyrosine was hypothesized. We tested the electron transport inhibitors 3-(3,4-dichlorophenyl)-1,1- dimethylurea, sodium azide, and 1,5-diphenylcarbazide and found distinct inhibition of nitration of PsbO1. We also propose a possible nitration mechanism.

PM2.5, SO2 and NO2 co-exposure impairs neurobehavior and induces mitochondrial injuries in the mouse brain

Air pollution is a serious environmental health problem that has been previously associated with neuropathological disorders. However, current experimental evidence mainly focuses on the adverse effects of a single air pollutant, ignoring the biological responses to the co-existence of these pollutants. In the present study, we co-exposed C57BL/6 J mice to PM2.5, SO2 and NO2 and explored their neurobehavior, histopathologic abnormalities, apoptosis-related protein expression and mitochondrial dysfunction. The results indicate that co-exposure to PM2.5, SO2 and NO2 impaired spatial learning and memory and caused abnormal expression of apoptosis-related genes (p53, bax and bcl-2). Additionally, these alterations were related to morphological changes in mitochondria, a reduction of ATP, the elevation of mitochondrial fission proteins and the downregulation of fusion proteins. These findings provide a basis for the understanding of mitochondrial abnormality-related neuropathological dysfunction in response to co-exposure to ambient air pollutants, which suggests an adaptive response to the frangibility of the central nerve system.

Differential abilities of nitrogen dioxide and nitrite to nitrate proteins in thylakoid membranes isolated from Arabidopsis leaves

Exposure of Arabidopsis leaves to nitrogen dioxide (NO2) results in nitration of specific chloroplast proteins. To determine whether NO2 itself and/or nitrite derived from NO2 can nitrate proteins, Arabidopsis thylakoid membranes were isolated and treated with NO2-bubbled or potassium nitrite (KNO2) buffer, followed by protein extraction, electrophoresis, and immunoblotting using an anti-3-nitrotyrosine (NT) antibody. NO2 concentrations in the NO2-bubbled buffer were calculated by numerically solving NO2 dissociation kinetic equations. The two buffers were adjusted to have identical nitrite concentrations. Both treatments yielded an NT-immunopositive band that LC/MS identified as PSBO1. The difference in the band intensity between the 2 treatments was designated nitration by NO2. Both NO2 and nitrite mediated nitration of proteins, and the nitration ability per unit NO2 concentration was ∼100-fold greater than that of nitrite.

Common ragweed (Ambrosia artemisiifolia L.): allergenicity and molecular characterization of pollen after plant exposure to elevated NO2

Ragweed pollen is the main cause of allergenic diseases in Northern America, and the weed has become a spreading neophyte in Europe. Climate change and air pollution are speculated to affect the allergenic potential of pollen. The objective of this study was to investigate the effects of NO2 , a major air pollutant, under controlled conditions, on the allergenicity of ragweed pollen. Ragweed was exposed to different levels of NO2 throughout the entire growing season, and its pollen further analysed. Spectroscopic analysis showed increased outer cell wall polymers and decreased amounts of pectin. Proteome studies using two-dimensional difference gel electrophoresis and liquid chromatography-tandem mass spectrometry indicated increased amounts of several Amb a 1 isoforms and of another allergen with great homology to enolase Hev b 9 from rubber tree. Analysis of protein S-nitrosylation identified nitrosylated proteins in pollen from both conditions, including Amb a 1 isoforms. However, elevated NO2 significantly enhanced the overall nitrosylation. Finally, we demonstrated increased overall pollen allergenicity by immunoblotting using ragweed antisera, showing a significantly higher allergenicity for Amb a 1. The data highlight a direct influence of elevated NO2 on the increased allergenicity of ragweed pollen and a direct correlation with an increased risk for human health.

Nitrogen Dioxide Sterilization in Low-Resource Environments: A Feasibility Study

Access to sterilization is a critical need for global healthcare, as it is one of the prerequisites for safe surgical care. Lack of sterilization capability has driven up healthcare infection rates as well as limited access to healthcare, especially in low-resource environments. Sterilization technology has for the most part been static and none of the established sterilization methods has been so far successfully adapted for use in low-resource environments on a large scale. It is evident that healthcare facilities in low-resource settings require reliable, deployable, durable, affordable, easily operable sterilization equipment that can operate independently of scarce resources. Recently commercialized nitrogen dioxide (NO2) sterilization technology was analyzed and adapted into a form factor suitable for use in low-resource environments. Lab testing was conducted in microbiological testing facilities simulating low-resource environments and in accordance with the requirements of the international sterilization standard ANSI/AAMI/ISO 14937 to assess effectiveness of the device and process. The feasibility of a portable sterilizer based on nitrogen dioxide has been demonstrated, showing that sterilization of medical instruments can occur in a form factor suitable for use in low-resource environments. If developed and deployed, NO2 sterilization technology will have the twin benefits of reducing healthcare acquired infections and limiting a major constraint for access to surgical care on a global scale. Additional benefits are achieved in reducing costs and biohazard waste generated by current health care initiatives that rely primarily on disposable kits, increasing the effectiveness and outreach of these initiatives.

Kinematic evidence that atmospheric nitrogen dioxide increases the rates of cell proliferation and enlargement to stimulate leaf expansion in Arabidopsis

To elucidate the stimulation of leaf growth by atmospheric nitrogen dioxide (NO2), we performed a kinematic analysis of the eighth leaves of Arabidopsis thaliana (accession C24) plants grown for 17-35 days after sowing in the presence or absence of 50 ppb NO2 (designated +NO2 plants and -NO2 plants, respectively). We found that the peak and mean values of the relative rates of leaf expansion, cell division and cell expansion were always greater in +NO2 plants than in -NO2 plants. No evidence for prolonged duration was obtained. Thus, NO2 treatment increased the rates of both cell proliferation and enlargement to increase leaf size. Furthermore, a fold-change analysis showed that cell proliferation and enlargement differentially regulated NO2-induced leaf expansion.

Exogenous sodium sulfide improves morphological and physiological responses of a hybrid Populus species to nitrogen dioxide

Gaseous nitrogen dioxide (NO2) can disturb normal plant growth and trigger complex physiological responses. NO2-induced responses are influenced by biotic or abiotic factors. In this study, we investigated the effects of exogenous sodium sulfide (Na2S, 5mmolL(-1)) on epidermis and stomata related physico-chemical responses of hybrid poplar cuttings (Pouplus alba×P. berolinensis) to gaseous NO2 (4μl1(-1)) for three time periods (0, 14 and 48h). We also investigated hydrogen sulfide (H2S), nitrate-nitrogen and nitrate reductase activity (NR) in control and Na2S treated plants. Our results showed that NO2 exposure for 48h led to the decline of NR, maximal PSII quantum yield (Fv/Fm), net photosynthetic rate (Pn), and dark respiration rate (Rd). The maximum rate for the post-illumination carbon dioxide burst (PIB) occurred in 48-h exposed leaves 13-15s after darkening. Moreover, NO2 exposure resulted in a significant increase in nitrogen percentage (from 0 to 33%) and a decrease in the macro and micro-elements of leaf surface. Spraying Na2S aqueous solution on the leaf surfaces significantly increased the thicknesses of palisade/spongy tissue and H2S content. Na2S pretreatment alleviated NO2-caused toxic effects as indicated by increased NR and higher values of Pn, Fv/Fm, and actual photochemical efficiency in light (ФPSII) compared with the control. Na2S pretreatment had no significant impacts on PIB-based photorespiration or elements composition of a leaf surface.

Differential responses of Arabidopsis thaliana accessions to atmospheric nitrogen dioxide at ambient concentrations

To better understand the response of plants to atmospheric nitrogen dioxide (NO2), we investigated biomass accumulation in 3 accessions of Arabidopsis thaliana: C24, Columbia (Col-0), and Landsberg erecta (Ler). Plants were grown in NO2-free air for 1 week after sowing, followed by 3 (Col-0 and Ler) to 4 (C24) weeks in air with or without NO 2 (10 or 50 ppb). NO2 treatment increased the biomass of all 3 accessions to varying extents. Treatment with 10 ppb NO2 increased shoot biomass in C24, Col-0, and Ler by 3.2-, 1.4-, and 2.3-fold, respectively, compared with control. Treatment with 50 ppb gave similar increases, except in C24 (2.7-fold). The physiological, evolutionary, and genetic significance of these results are discussed below.

Nitrogen dioxide regulates organ growth by controlling cell proliferation and enlargement in Arabidopsis

• To gain more insight into the physiological function of nitrogen dioxide (NO₂), we investigated the effects of exogenous NO₂ on growth in Arabidopsis thaliana. • Plants were grown in air without NO₂ for 1 wk after sowing and then grown for 1-4 wk in air with (designated treated plants) or without (control plants) NO₂. Plants were irrigated semiweekly with a nutrient solution containing 19.7 mM nitrate and 10.3 mM ammonium. • Five-week-old plants treated with 50 ppb NO₂ showed a ≤ 2.8-fold increase in biomass relative to controls. Treated plants also showed early flowering. The magnitude of the effects of NO₂ on leaf expansion, cell proliferation and enlargement was greater in developing than in maturing leaves. Leaf areas were 1.3-8.4 times larger on treated plants than corresponding leaves on control plants. The NO₂-induced increase in leaf size was largely attributable to cell proliferation in developing leaves, but was attributable to both cell proliferation and enlargement in maturing leaves. The expression of different sets of genes for cell proliferation and/or enlargement was induced by NO₂, but depended on the leaf developmental stage. • Collectively, these results indicated that NO₂ regulates organ growth by controlling cell proliferation and enlargement.

Nitrogen dioxide is a positive regulator of plant growth

Atmospheric nitric oxide (NO) and nitrogen dioxide (NO₂) have long been recognized as either detrimental or beneficial for plant development. Recent research has established that NO is a phytohormone. Our present knowledge of the physiological role of NO₂ is incomplete. We do know, however, that exogenous NO₂ positively regulates the vegetative and reproductive growth of plants. We may therefore postulate that NO₂ is a positive growth regulator for plants. We are now in a position to coherently summarize what is known of NO₂ physiology; collated information on the topic is presented here.

Nitrogen dioxide accelerates flowering without changing the number of leaves at flowering in Arabidopsis thaliana

A negative correlation has consistently been reported between the change in flowering time and the change in leaf number at flowering in response to environmental stimuli, such as the application of exogenous compounds, cold temperature, day length and light quality treatments in Arabidopsis thaliana (Arabidopsis). However, we show here that the application of exogenous nitrogen dioxide (NO2) did not change the number of rosette leaves at flowering, but actually accelerated flowering in Arabidopsis. Furthermore, NO2 treatment was found to increase the rate of leaf appearance. Based on these results, reaching the maximum rosette leaf number earlier in response to NO2 treatment resulted in earlier flowering relative to controls.

Effect of combined nitrogen dioxide and carbon nanoparticle exposure on lung function during ovalbumin sensitization in Brown Norway rat

The interaction of particulate and gaseous pollutants in their effects on the severity of allergic inflammation and airway responsiveness are not well understood. We assessed the effect of exposure to NO₂ in the presence or absence of repetitive treatment with carbon nanoparticle (CNP) during allergen sensitization and challenges in Borwn-Norway (BN) rat, in order to assess their interactions on lung function and airway responses (AR) to allergen and methacholine (MCH), end-expiratory lung volume (EELV), bronchoalveolar lavage fluid (BALF) cellular content, serum and BALF cytokine levels and histological changes. Animals were divided into the following groups (n = 6): Control; CNP (Degussa-FW2): 13 nm, 0.5 mg/kg instilled intratracheally ×3 at 7-day intervals; OVA: ovalbumin-sensitised; OVA+CNP: both sensitized and exposed to CNP. Rats were divided into equal groups exposed either to air or to NO₂, 10 ppm, 6 h/d, 5d/wk for 4 weeks. Exposure to NO₂, significantly enhanced lung inflammation and airway reactivity, with a significantly larger effect in animals sensitized to allergen, which was related to a higher expression of TH1 and TH2-type cytokines. Conversely, exposure to NO₂ in animals undergoing repeated tracheal instillation of CNP alone, increased BALF neutrophilia and enhanced the expression of TH1 cytokines: TNF-α and IFN-γ, but did not show an additive effect on airway reactivity in comparison to NO₂ alone. The exposure to NO₂ combined with CNP treatment and allergen sensitization however, unexpectedly resulted in a significant decrease in both airway reactivity to allergen and to methacholine, and a reduction in TH2-type cytokines compared to allergen sensitization alone. EELV was significantly reduced with sensitization, CNP treatment or both. These data suggest an immunomodulatory effect of repeated tracheal instillation of CNP on the proinflammatory effects of NO₂ exposure in sensitized BN rat. Furthermore, our findings suggest that NO₂, CNP and OVA sensitization may significantly slow overall lung growth in parenchymally mature animals.

Desferrioxamine inhibits protein tyrosine nitration: mechanisms and implications

Tissues are exposed to exogenous and endogenous nitrogen dioxide ((·)NO(2)), which is the terminal agent in protein tyrosine nitration. Besides iron chelation, the hydroxamic acid (HA) desferrioxamine (DFO) shows multiple functionalities including nitration inhibition. To investigate mechanisms whereby DFO affects 3-nitrotyrosine (3-NT) formation, we utilized gas-phase (·)NO(2) exposures, to limit introduction of other reactive species, and a lung surface model wherein red cell membranes (RCM) were immobilized under a defined aqueous film. When RCM were exposed to ()NO(2) covered by +/- DFO: (i) DFO inhibited 3-NT formation more effectively than other HA and non-HA chelators; (ii) 3-NT inhibition occurred at very low[DFO] for prolonged times; and (iii) 3-NT formation was iron independent but inhibition required DFO present. DFO poorly reacted with (·)NO(2) compared to ascorbate, assessed via (·)NO(2) reactive absorption and aqueous-phase oxidation rates, yet limited 3-NT formation at far lower concentrations. DFO also inhibited nitration under aqueous bulk-phase conditions, and inhibited 3-NT generated by active myeloperoxidase "bound" to RCM. Per the above and kinetic analyses suggesting preferential DFO versus (·)NO(2) reaction within membranes, we conclude that DFO inhibits 3-NT formation predominantly by facile repair of the tyrosyl radical intermediate, which prevents (·)NO(2) addition, and thus nitration, and potentially influences biochemical functionalities.

Synthesis, spectroscopic characterization and biological activities of N₄O₂ Schiff base ligand and its metal complexes of Co(II), Ni(II), Cu(II) and Zn(II)

The Schiff base ligand, bis(indoline-2-one)triethylenetetramine (L) obtained from condensation of triethylenetetramine and isatin was used to synthesize the complexes of type, [ML]Cl(2) [M=Co(II), Ni(II), Cu(II) and Zn(II)]. L was characterized on the basis of the results of elemental analysis, FT-IR, (1)H and (13)C NMR, mass spectroscopic studies. The stoichiometry, bonding and stereochemistries of complexes were ascertained on the basis of results of elemental analysis, magnetic susceptibility values, molar conductance and various spectroscopic studies. EPR, UV-vis and magnetic moments revealed an octahedral geometry for complexes. L and its Cu(II) and Zn(II) complexes were screened for their antibacterial activity. Analgesic activity of Cu(II) and Zn(II) complexes was also tested in rats by tail flick method. Both complexes were found to possess good antibacterial and moderate analgesic activity.

Lack of effect of nitrogen dioxide exposure on heart rate variability in patients with stable coronary heart disease and impaired left ventricular systolic function

OBJECTIVES

Epidemiological studies of air pollution on cardiovascular health show associations of cardiac mortality and admissions with exposure to nitrogen dioxide (NO(2)) at low concentrations. These associations could be causal or NO(2) could be acting as a surrogate measure for another air pollutant, most likely ultrafine particles. No studies of cardiac susceptibility to acute exposure to NO(2) have been undertaken.

METHODS

Randomised controlled exposures to NO(2) (400 ppb for 1 h) and air in subjects with coronary heart disease and impaired left ventricular systolic function not taking β adrenoceptor blocking drugs.

RESULTS

There were no significant changes in heart rate, blood pressure, leucocyte coping capacity or any heart rate variability measure following NO(2) exposure compared with air.

CONCLUSION

These findings suggest that NO(2) does not affect heart rate variability at these concentrations (which are high for urban background levels) and in the absence of other pollutants. While a synergistic effect has not been ruled out, these data lend support to the idea that the epidemiological data associating cardiac outcomes with NO(2) are more likely due to an associated pollutant rather than NO(2) itself.

Responses of sugar maple and hemlock seedlings to elevated carbon dioxide under altered above- and belowground nitrogen sources

Various human-induced changes to the atmosphere have caused carbon dioxide (CO₂), nitrogen dioxide (NO₂) and nitrate deposition (NO₃⁻) to increase in many regions of the world. The goal of this study was to examine the simultaneous influence of these three factors on tree seedlings. We used open-top chambers to fumigate sugar maple (Acer saccharum) and eastern hemlock (Tsuga canadensis) with ambient or elevated CO₂ and NO₂ (elevated concentrations were 760 ppm and 40 ppb, respectively). In addition, we applied an artificial wet deposition of 30 kg ha⁻¹ year⁻¹ NO₃⁻ to half of the open-top chambers. After two growing seasons, hemlocks showed a stimulation of growth under elevated CO₂, but the addition of elevated NO₂ or NO₃⁻ eliminated this effect. In contrast, sugar maple seedlings showed no growth enhancement under elevated CO₂ alone and decreased growth in the presence of NO₂ or NO₃⁻, and the combined treatments of elevated CO₂ with increased NO₂ or NO₃⁻ were similar to control plants. Elevated CO₂ induced changes in the leaf characteristics of both species, including decreased specific leaf area, decreased %N and increased C:N. The effects of elevated CO₂, NO₂ and NO₃⁻ on growth were not additive and treatments that singly had no effect often modified the effects of other treatments. The growth of both maple and hemlock seedlings under the full combination of treatments (CO₂ + NO₂ + NO₃⁻) was similar to that of seedlings grown under control conditions, suggesting that models predicting increased seedling growth under future atmospheric conditions may be overestimating the growth and carbon storage potential of young trees.

[Broncholytic effect of prednisolon in the rats inhaled with nitrogen dioxide]

In the rat model of chronic obstructive pulmonary disease, the dilatation effect of prednisolon was most obvious after 15 days of nitrogen dioxide inhalation. In a longer inhalation, the dilatation effect decreases, and on the 90th day of the inhalation prednisolon enhances contraction of the trachea and bronchi. Prednisolon seems to act upon the respiratory tract via interaction with endings of afferent C-fibres. In prolonged inhalation of nitrogen dioxide, resistance against corticosteroids develops as the result of the C-fibre ending inactivation.

Salicylic acid-altering arabidopsis mutants response to NO(2) exposure

Nitrogen dioxide (NO(2))-induced responses in wild type (wt) and salicylic acid (SA)-altering Arabidopsis mutants snc1 (suppressor of npr1-1, constitutive) with high SA level, transgenic line nahG with low SA level, npr1-1 (nonexpressor of PR gene) with SA signaling blockage and double mutant snc1nahG plants, were investigated. All mutant lines except sncl showed that NO(2) exposure at 0.25 microL L(-1) increased chlorophyll content and biomass accumulation, elevated photosynthetic rate, and decreased MDA content compared to their respective controls. The sncl plants were similar to the control plants for these measured indices. NO(2) exposure at 0.5 microL L(-1) and higher doses caused injury to wt, nahG, npr1-1 and snc1nahG plants, whereas the snc1 plants exhibited a stronger tolerance. To evaluate the resistance mechanism, we further investigated the changes in the mutants exposed to 1 microL L(-1) of NO(2) in relation to endogenous SA level, antioxidant capacity and redox status. The collected data demonstrated that the NO(2) tolerance in snc1, with a high SA level, was tightly linked to the increased antioxidant capacity and decreased oxidative stress. This suggests that SA may play an important protective function in plant response to NO(2) stress.

Synergistic action of exogenous salicylic acid and arbuscular mycorrhizal fungus colonization in Avena nuda seedlings in response to NO(2) exposure

Colonization of arbuscular mycorrhizal fungi Glomus mosseae or exogenous salicylic acid (SA) treatment can increase Avena nuda plant tolerance to elevated NO(2) exposure. The combination of the two factors, namely application of SA to the mycorrhizal plants, further promoted NO(2) tolerance, as indicated by an alleviated plant biomass decrease compared to the respective treatment. The analysis of antioxidant capacity, redox status and photon energy utilization showed that the increased NO(2) tolerance in the treated plants may be associated, at least in part, with scavenging reactive oxygen species, maintaining CO(2) assimilated rate and reducing conditions in cells.

Molecular characterization of atmospheric NO2-responsive germin-like proteins in azalea leaves

Atmospheric nitrogen dioxide (NO(2)) is an environmental oxidant that is removed through direct uptake by foliage, but plant responses to this highly reactive gas are not well understood at the molecular level. From NO(2)-exposed leaves of a woody azalea (Rhododendron mucronatum), we cloned two cDNAs (RmGLP1 and RmGLP2) for germin-like proteins (GLPs), a group of ubiquitous plant proteins that have been implicated in various plant physiological and developmental processes. Quantitative analysis of mRNA expression, together with immunoblotting data, showed that foliar exposure to NO(2) caused a robust induction of these GLP-encoding genes. When produced in tobacco cell culture, recombinant RmGLP2 was secreted into the apoplast, where it exhibited superoxide dismutase activity. RmGLP1 and RmGLP2 represent the first examples of plant genes that are responsive to airborne NO(2). These enzymes might have a potential role in extracellular defense mechanisms through attenuation of interactions between reactive nitrogen and oxygen species.

The effects of nitronium ion on nitration, carbonylation and coagulation of human fibrinogen

The effect of nitronium ion on nitration, carbonylation and coagulation of human fibrinogen (Fg) in vitro was investigated. We observed that nitration of tyrosine, induced by NO2BF4 (0.01 mmol/l), was increased. No changes in carbonylation by NO2BF4 (0.01 mmol/l) were noticed. Mentioned alterations were associated with amplified coagulation of Fg. Higher concentrations of NO2BF4 (1 and 0.1 mmol/l) triggered growth of nitration and carbonylation of Fg, but led to inhibition of polymerization. Slight nitration may be responsible for increase, whereas sizable nitration and oxidation may lead to inhibition of Fg coagulation.

Nitrogen dioxide at an ambient level improves the capability of kenaf (Hibiscus cannabinus) to decontaminate cadmium

As reported previously, atmospheric nitrogen dioxide (NO2) at an ambient level increased plant size and the contents of cell constituents. We investigated this effect of atmospheric NO2 on decontamination of cadmium (Cd) by kenaf (Hibiscus cannabinus). Seventeen-day-old seedlings of kenaf were grown in air either with NO2 or without NO2. (Plants were exposed to 100 +/- 50 ppb NO2 for 10 d under irrigation of 0.1% Hyponex supplemented with 20 microM CdCl2.) Plants were then harvested and the biomass of stems, leaves, and roots, as well as the content of Cd in the organs, was determined. The stem and root biomass per plant were 1.25-1.27-fold greater in +NO2 plants than in -NO2 plants. The Cd content per stem was more than 30% greater in +NO2 plants than in -NO2 plants.

Nitrogen dioxide induces apoptosis and proliferation but not emphysema in rat lungs

BACKGROUND

Apoptosis of alveolar septal cells has been linked to emphysema formation. Nitrogen dioxide, a component of cigarette smoke, has been shown to induce alveolar epithelial cell apoptosis in vitro. It is hypothesised that exposure of rats to nitrogen dioxide may result in increased alveolar septal cell apoptosis in vivo with ensuing emphysema-that is, airspace enlargement and loss of alveolar walls.

METHODS

Fischer 344 rats were exposed to 10 ppm nitrogen dioxide for 3, 7, 21 days or 21 days followed by 28 days at room air. Age-matched control rats were exposed to room air for 3, 21 or 49 days. Lungs fixed at 20 cm fluid column, embedded in paraffin wax, glycol methacrylate and araldite, were analysed by design-based stereology. Alveolar septal cell apoptosis (transferase dUTP nick end labelling assay, active caspase 3) and proliferation (Ki-67), airspace enlargement, total alveolar surface area, and absolute alveolar septal volume as well as the ultrastructural composition of the alveolar wall were quantified.

RESULTS

Nitrogen dioxide resulted in an eightfold increase in alveolar septal cell apoptosis at day 3 and a 14-fold increase in proliferation compared with age-matched controls. Airspace enlargement, indicated by a 20% increase in mean airspace chord length, was evident by day 7 but was not associated with loss of alveolar walls. By contrast, nitrogen dioxide resulted in an increase in the total surface area and absolute volume of alveolar walls comprising all compartments. The ratio of collagen to elastin, however, was reduced at day 21. Lungs exposed to nitrogen dioxide for 21 days exhibited quantitative structural characteristics as seen in control lungs on day 49.

CONCLUSIONS

Nitrogen dioxide exposure of rats results in increased alveolar septal cell turnover leading to accelerated lung growth, which is associated with an imbalance in the relative composition of the extracellular matrix, but fails to induce emphysema.

Is general anesthesia a risk for myocardium? Effect of anesthesia on myocardial function as assessed by cardiac troponin-i in two different groups (isofluran+N2O inhalation and propofol+fentanyl iv anesthesia)

BACKGROUND AND OBJECTIVES

Peroperative myocardial infarction (MI) is the most common cause of morbidity and mortality. What is the role of general anesthesia in this process? Is general anesthesia a risk for myocardial infarction? The present study was designed to determine whether the measurement of serum levels of cardiac troponin I (cTnI), a highly sensitive and specific marker for cardiac injury, would help establish the diagnosis of myocardial infarction in two different types of anesthesia.

METHOD

Elective abdominal hysterectomy was planned with the permission of the ethic committee in 40 patients who were 20-45 years range, in ASA-I group, and have a Goldman Cardiac Risk Index-0. The patients were divided into two groups. Isoflurane + N2O was administrated to first group, and Propofol + Fentanyl to second group. cTnI levels were determined before anesthesia, after induction before surgery and 9 hours after the second period respectively.

RESULTS

There was no significant difference between the groups by the means of demographic properties, hemodynamic parameters and cTnI levels, and the cTnI levels were determined under the basal levels in all samples.

CONCLUSION

General anesthesia is not a risk for myocardial infarction to state eliminating risk factors and protection hemodynamia cardiac.

S-phase arrest by reactive nitrogen species is bypassed by okadaic acid, an inhibitor of protein phosphatases PP1/PP2A

In mammalian cells DNA damage activates a checkpoint that halts progression through S phase. To determine the ability of nitrating agents to induce S-phase arrest, mouse C10 cells synchronized in S phase were treated with nitrogen dioxide (NO(2)) or SIN-1, a generator of reactive nitrogen species (RNS). SIN-1 or NO(2) induced S-phase arrest in a dose- and time-dependent manner. As for the positive controls adozelesin and cisplatin, arrest was accompanied by phosphorylation of ATM kinase; dephosphorylation of pRB; decreases in RF-C, cyclin D1, Cdc25A, and Cdc6; and increases in p21. Comet assays indicated that RNS induce minimal DNA damage. Moreover, in a cell-free replication system, nuclei from cells treated with RNS were able to support control levels of DNA synthesis when incubated in cytosolic extracts from untreated cells, whereas nuclei from cells treated with cisplatin were not. Induction of phosphatase activity may represent one mechanism of RNS-induced arrest, for the PP1/PP2A phosphatase inhibitor okadaic acid inhibited dephosphorylation of pRB; prevented decreases in the levels of RF-C, cyclin D1, Cdc6, and Cdc25A; and bypassed arrest by SIN-1 or NO(2), but not cisplatin or adozelesin. Our studies suggest that RNS may induce S-phase arrest through mechanisms that differ from those elicited by classical DNA-damaging agents.

Nitrogen dioxide enhances allergic airway inflammation and hyperresponsiveness in the mouse

In addition to being an air pollutant, NO2 is a potent inflammatory oxidant generated endogenously by myeloperoxidase and eosinophil peroxidase. In these studies, we sought to determine the effects of NO2 exposure on mice with ongoing allergic airway disease pathology. Mice were sensitized and challenged with the antigen ovalbumin (OVA) to generate airway inflammation and subsequently exposed to 5 or 25 ppm NO2 for 3 days or 5 days followed by a 20-day recovery period. Whereas 5 ppm NO2 elicited no pathological changes, inhalation of 25 ppm NO2 alone induced acute lung injury, which peaked after 3 days and was characterized by increases in protein, LDH, and neutrophils recovered by BAL, as well as lesions within terminal bronchioles. Importantly, 25 ppm NO2 was also sufficient to cause AHR in mice, a cardinal feature of asthma. The inflammatory changes were ameliorated after 5 days of inhalation and completely resolved after 20 days of recovery after the 5-day inhalation. In contrast, in mice immunized and challenged with OVA, inhalation of 25 ppm NO2 caused a marked augmentation of eosinophilic inflammation and terminal bronchiolar lesions, which extended significantly into the alveoli. Moreover, 20 days postcessation of the 5-day 25 ppm NO2 inhalation regimen, eosinophilic and neutrophilic inflammation, pulmonary lesions, and AHR were still present in mice immunized and challenged with OVA. Collectively, these observations suggest an important role for NO2 in airway pathologies associated with asthma, both in modulation of degree and duration of inflammatory response, as well as in induction of AHR.

Does nitrogen dioxide affect inflammatory markers after nasal allergen challenge?

BACKGROUND

Exposure to high ambient levels of nitrogen dioxide (NO2) enhances the bronchial inflammatory reaction to allergen in humans. We tested whether this NO2 effect occurs also in the upper airways.

METHODS

Sixteen allergic subjects with rhinitis and mild asthma were exposed at rest to either purified air or 500 microg/m3 NO2 for 30 minutes, followed 4 hours later by a nasal allergen challenge. Nasal lavage was performed before air/NO2 exposure, before allergen challenge, and 1, 4 and 18 hours after allergen challenge. Symptoms were recorded.

RESULTS

The percentage of eosinophils and neutrophils, eosinophil cationic protein, and myeloperoxidase were similar after exposure to air + allergen and to NO2 + allergen. We noticed a tendency to increased sneezing the day after exposure to NO2 + allergen.

CONCLUSION

The priming effect of an ambient brief NO2 exposure on subsequent allergic response was not noticeable in activation of inflammatory cells and mediators in the upper airways.

3-nitrotyrosine attenuates respiratory syncytial virus infection in human bronchial epithelial cell line

3-nitrotyrosine (NO2Tyr), an L-tyrosine derivative during nitrative stress, can substitute the COOH-terminal tyrosine of alpha-tubulin, posttranslationally altering microtubular functions. Because infection of the cells by respiratory syncytial virus (RSV) may require intact microtubules, we tested the hypothesis that NO2Tyr would inhibit RSV infection and intracellular signaling via nitrotyrosination of alpha-tubulin. A human bronchial epithelial cell line (BEAS-2B) was incubated with RSV with or without NO2Tyr. The release of chemokines and viral particles and activation of interferon regulatory factor-3 (IRF-3) were measured. Incubation with NO2Tyr increased nitrotyrosinated alpha-tubulin, and NO2Tyr colocalized with microtubules. RSV-infected cells released viral particles, RANTES, and IL-8 in a time- and dose-dependent manner, and intracellular RSV proteins coprecipitated with alpha-tubulin. NO2Tyr attenuated the RSV-induced release of RANTES, IL-8, and viral particles by 50-90% and decreased alpha-tubulin-associated RSV proteins. 3-chlorotyrosine, another L-tyrosine derivative, had no effects. NO2Tyr also inhibited the RSV-induced shift of the unphosphorylated form I of IRF-3 to the phosphorylated form II. Pre-exposure of the cells to NO(2) (0.15 ppm, 4 h), which produced diffuse protein tyrosine nitration, did not affect RSV-induced release of RANTES, IL-8, or viral particles. NO2Tyr did not affect the potential of viral spreading to the neighboring cells since the RSV titers were not decreased when the uninfected cells were cocultured with the preinfected cells in NO2Tyr-containing medium. These results indicate that NO2Tyr, by replacing the COOH-terminal tyrosine of alpha-tubulin, attenuated RSV infection, and the inhibition appeared to occur at the early stages of RSV infection.

Effects of a novel gaseous antioxidative system containing a rosemary extract on the oxidation induced by nitrogen dioxide and ultraviolet radiation

Rosemary is commonly used as a spice and a flavoring agent in food processing. Although the antioxidative properties of its extracts have been investigated, there have been few reports on the volatile components of rosemary. We designed a novel antioxidative system which can generate the volatile constituents in the gaseous phase from a rosemary extract and evaluated the gaseous antioxidative activities against both lipid peroxidation and cell death induced by nitrogen dioxide and ultraviolet radiation. The antioxidative effects of the major volatile components on the oxidation of linoleic acid induced by azo compounds were also investigated in a solution. The volatile components in the novel antioxidative system suppressed the Jurkat cell death induced by nitrogen dioxide and the intracellular formation of reactive oxygen species in fibroblast cells induced by ultraviolet radiation. 1,8-Cineole among the volatile components exerted an antioxidative effect against the oxidation of linoleic acid in a solution induced by azo compounds and ultraviolet radiation. These data suggest that the volatile constituents of a rosemary extract had antioxidative properties and that gaseous exposure antioxidant is a promising method for promoting health.

Voltammetric studies of hemoglobin-coated polystyrene latex bead films on pyrolytic graphite electrodes

A novel hemoglobin (Hb)-coated polystyrene (PS) latex bead film was deposited on pyrolytic graphite (PG) electrode surface. In the first step, positively charged Hb molecules in pH 5.0 buffers were adsorbed on the surface of negatively charged, 500 nm diameter PS latex beads bearing sulfate groups by electrostatic interaction. The aqueous dispersion of Hb-coated PS particles was then deposited on the surface of PG electrodes and, after evaporation of the solvent, Hb-PS films were formed. The Hb-PS film electrodes exhibited a pair of well-defined, quasi-reversible cyclic voltammetric (CV) peaks at about -0.36 V vs. SCE in pH 7.0 buffers, characteristic of Hb heme Fe(III)/Fe(II) redox couples. Positions of Soret absorption band of Hb-PS films suggest that Hb retains its near-native structure in the films in its dry form and in solution at medium pH. The Hb in PS films was also acted as a catalyst to catalyze electrochemical reduction of various substrates such as trichloroacetic acid (TCA), nitrite, oxygen and hydrogen peroxide.